Under Review: The Apple Watch Series 3's Fitness Functions

If you’ve heard elsewhere that the Apple Watch Series 3 sucks as a phone substitute, our retort is simple: Duh! Sure, you’ll only get an hour of talk time on the tiny device that, ahem, is still far smaller than the bruisingly large wrist-puters that the competition offers with LTE SIMs. The point, as Apple continues to push the envelope on fitness, is to have an untethered timepiece that pairs to any Bluetooth earbuds (or, of course, to Apple’s excellent AirPods) that can also save your bacon just in case you get stuck.

As for our testing, so far Apple Watch Series 3 has done most of what we’d hope for, with just a few head scratchers..

Heart Rate

Note the graph to the left. It shows a day view of my heart rate. The way the Watch, both Series 2 and Series 3, captures HR is by taking a very short, few-second sample of the beat interval. During testing with Series 2 over the past year, and more recently with Series 3, we’ve found the Apple Watch is generally very good at capturing heart rate during fitness. We’ve seen some aberration during exercises with a lot of wrist movement, such as jumping rope, and Apple even warns users that capturing heart rate is an imperfect art. That fact alone is praiseworthy. No wrist-worn wearable we’ve tested is as accurate as an EKG chest strap (that isn’t trying to read your pulse via light profusion, a la the Watch, but instead reads the electrical impulses of your heart directly). Still, if you’re loath to wear a strap, the Watch is state of the art for heart rate capture at the wrist, and we give Apple props for constant improvement, and for adding heart rate recovery and resting rates as stats you can now see right on your wrist during the day and post-workout.

Apple also added a function (also works with legacy Apple Watches) that will notify users if their heart rate spikes at least three times over the period of ten minutes while a wearer is sedentary; since the Watch senses motion it can discern between when you’re moving and not, even if you don’t tell the Watch you’re working out. An elevated heart rate when you’re sitting at your desk and stressing about work could be indicative of a panic attack a heart condition. Apple says it lets users set the rate at which this triggers an alert (rather than use its vast trove of extensive research that would indicate a constant 140bpm when you’re sitting still is unhealthy), because they’re not in the business of giving health advice. The other way to say that: They’d need FDA approval to do so, and no wearables maker wants to get this wrong. Apple’s treading carefully here, trying to help people who might have heart conditions or suffer from panic attacks, but they’re still not ready to replace your physician, or deal with the red tape the FDA might require.

As for recovery and resting heart rate data, it’s semi-useless to most of us at the moment, because it’s not advisory. But Apple is very confident that third-party app developers are going to harvest the information to issue advice on when to go hard and when you need to bake in another rest day.

Garmin, Suunto, Polar, et al, use recovery info for precisely this scenario. Given the fact that you can already run apps on Apple Watch from Under Armor, Nike, Strava, Wahoo Fitness, Runkeeper and Runtastic (and hundreds more), it’s inevitable that every app maker that can, will take advantage of the new data to be more prescriptive.

Improved Fitness Metrics

Speaking of which, one major upgrade to Series 3 is far faster app loading times. Using Strava to track part of an interval and strength workout the app loaded immediately and showed us a shrunken version of the phone app, with average pace and distance as well as splits. After the workout the portion recorded via Strava immediately ported to the iPhone 8 Plus (and would do so with any iPhone) and then to the cloud, so my posse could see it in my Strava activity feed. On the app on the phone I could see more granular metrics including pace analysis, heart rate, heart rate zones, splits, etc.

Separately the new High Intensity Interval Training mode of Apple’s native Workout app (which now also includes a lot more options, like cross training, open water swimming, snow sports, etc.) reveals a secret sauce heart-rate mode. In HIIT the Watch is looking not just at your average beats per second, but at recovery as well between bouts of effort. The goal is to target the training effect of both a lactate threshold effort and that your heart rate is falling effectively enough for recovery before the next cycle of work. This is good stuff, but what's not clear is if Apple is opening up this longer heart rate/recovery capture to third-party app developers. Still, that is our expectation, and we'd bet we’ll see the data used in more granular fashion for everything from spinning and rowing-specific apps to Crossfit.

The new barometric altimeter is one addition we were very happy to see. It’s pretty old-school tech; ABC watches have had it for ages. Here Apple’s using it in the background to more accurately count flights climbed and to over-lay with GPS metrics so your total elevation gained and lost during workouts is more precise. Again, you can expect specific third-party apps to salivate over the possibilities; consider backcountry-specific skiing apps that couldn’t reliably track elevation with GPS alone, but now can get a more accurate reading with this dual sensing.

Apple also anticipates greater use of the SIM. As we predicted, Apple anticipates that app makers will use SIM data to live-update metrics as you work out, so you’ll see the fastest mile being run in your area, but, again potentially, also the five people running about the same speed as you, so you could live pace-set off your fellow sweaters. “Live” Nike Run Club? It’s a pretty cool idea.

Still in beta, but so far so good, is pairing tunes. Apple now automatically ports over a New Music and Favorites mix from Apple Music to the Watch app on your phone and to your wrist, but you can also tweak it, to add songs in Heavy Rotation, and as before, custom add songs, albums, etc., that you want to have access to from your wrist. That presumes you have an Apple Music account; Apple will also allow live streaming to the Series 3 later this fall, but at least for now that will only be in the Apple ecosystem, meaning using your iCloud Music library, Radio and Beats 1 streams.

The Phone on Your Wrist

We tested both texting and on-wrist calling and it worked seamlessly, no phone nearby or even on. But it will cost you a bit more from your carrier. We do like that users don’t have to give loved ones another cell number; any incoming call made to your iPhone will automatically bounce to your Watch if the two devices aren’t within pairing range. Ditto, calling from your wrist will ID the incoming call as from you, not a number your posse can’t identify. But, yes, having a Watch Series 3 with LTE is yet another “leak” in your wallet.

*This post has been updated. Apple’s Heart Rate study with Stanford University is not linked to the function that allows elevated heart rate tracking. An earlier version of this entry also failed to explain how heart rate is captured during HIIT workouts.